Sensing Mechanism and Excited-State Dynamics of a Widely Used Intracellular Fluorescent pH Probe: pHrodo.

ABSTRACT: The pHrodo with an "off-on" response to the changes of pH has been widely used as a fluorescent pH probe for bioimaging. The fluorescence off-on mechanism is fundamentally important for its application and further development. Herein, the sensing mechanism, especially the relevant excited-state dynamics, of pHrodo is investigated by steady-state and time-resolved spectroscopy as well as quantum chemical calculations, showing that pHrodo is best understood using the bichromophore model. Its first excited state (S₁) is a charge transfer state between two chromophores. From S₁, pHrodo relaxes to its ground state (S₀) via an ultrafast nonradiative process (∼0.5 ps), which causes its fluorescence to be "off". After protonation, S₁ becomes a localized

SUBMITTER: Jiang S 

PROVIDER: S-EPMC10683063 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature